The Glossary of Historic Building Surveying

  • /ˌæntiˈskreɪp/ (conservation philosophy) The nickname of the Society for the Protection of Ancient Buildings (SPAB), founded by William Morris in 1877, and by extension the conservative repair philosophy it promoted. Morris's founding letter to the Athenaeum was prompted by George Gilbert Scott's proposed restoration of Tewkesbury Abbey. The term refers to the Victorian practice of scraping plaster and limewash from church interiors and re-dressing weathered stone, which the Society opposed along with wholesale restoration to a conjectured original state. The SPAB Manifesto called for protection in place of restoration, regular maintenance to stave off decay, and repair that is honest and distinguishable from original fabric. The position drew on Ruskin's argument in The Seven Lamps of Architecture (1849) that restoration destroys authenticity. It stood against the approach of Viollet-le-Duc, who defined restoration as reinstating a building to a state of completeness that may never have existed. Its principles of minimal intervention and honest repair are reflected in the Venice Charter (1964) and remain central to UK practice.

  • /ˈæʃlə/ (masonry) Masonry of squared, dressed blocks laid in regular courses with fine joints, in contrast to rubble walling of undressed or roughly shaped stone. Surface finishes include rubbed, tooled, droved, vermiculated and rusticated work, and the character of tooling can assist dating. Ashlar is frequently a facing over a rubble or brick core, tied by occasional through-stones, and separation of facing from core can present as bulging or hollow-sounding areas. Sedimentary stone should be laid on its natural bed, with the bedding planes horizontal. Face-bedded stone, set with the bedding planes parallel to the wall face, is prone to delamination and is a common defect in both historic work and poorly specified repairs. Projecting features such as cornices and copings are conventionally edge-bedded, with the planes vertical and perpendicular to the face.

A

  • /ˈbresəmə/ (timber construction) A principal horizontal beam carrying a wall or structure above a wide opening. In timber-framed buildings it denotes the beam at the front of a jetty, carrying the studs of the projecting upper storey. In vernacular interiors it describes the large beam spanning an inglenook fireplace. Spellings vary (breastsummer, bressummer). The word combines breast with summer, the latter from the Old French sommier, a beast of burden and hence a load-bearing beam. Fireplace bressumers are prone to charring and to decay where their bearings are built into damp masonry. They also frequently carry burn marks and incised symbols, whose interpretation as deliberate apotropaic protection remains debated, and these should be recorded before any repair.

B

  • /ˈkɑːpəntəz ˌmɑːks/ (timber analysis) Assembly marks cut or scribed on timbers in the framing yard so that prefabricated joints could be matched when the frame was re-erected on site. They typically use numeral sequences derived from Roman numerals, applied with a chisel, gouge or race knife, with additional tags distinguishing opposite sides or frames. A consistent sequence supports the interpretation of a frame as a single build in its original position. Breaks in sequence, mixed systems, or marks in illogical positions may indicate reused timber, alteration or reassembly. Carpenters' marks should be distinguished from masons' marks, merchants' marks on imported Baltic timber, and ritual or protective marks. Hewett (1980) remains a standard reference on the development of English framing.

  • /ˈklɪəstɔːri/ (ecclesiastical architecture) The upper stage of the main walls of a nave, choir or transept, rising above the aisle roofs and pierced by windows. The word derives from clear storey, meaning a lit storey. In great churches it forms the uppermost level of the elevation, above the arcade and triforium. In English parish churches clerestories were frequently added in the fifteenth and early sixteenth centuries, often together with a reduction to a low-pitched lead roof. That sequence is often legible in the weathering course or roof crease on the east face of the west tower, which records the line of an earlier and steeper nave roof. Clerestory walls are thin, stand on arcades and carry roof loads, so outward lean of the walls and distortion of the arcades should be examined together.

  • /kɒb/ (earth construction) Monolithic earth walling built from subsoil mixed with water and fibre, usually straw, sometimes with added aggregate. The mix is placed in successive lifts, trodden and consolidated, allowed to dry, and pared to a face before the next lift is added. Cob is associated principally with Devon and the south-west, with chalk-based variants in Hampshire, Wiltshire and Dorset. Related earth traditions include witchert in Buckinghamshire and clay lump in East Anglia, the latter formed of unfired blocks. The material performs well when kept dry at the base and head, the basis of the traditional advice that cob needs a good hat and good boots. Its principal vulnerability is saturation, which can cause sudden structural collapse. Cement renders, impermeable paints and raised external ground levels are the most common causes of failure, and repair relies on compatible earth materials, lime renders and limewash.

  • /krʌk/ (timber framing) A structural frame formed by pairs of large inclined timbers, called blades, rising from at or near ground level to meet at or near the ridge. Blades were commonly obtained by splitting a single curved tree to give a matched pair. Crucks carry the roof directly, and the walls are frequently non-structural. Variants include full, base, raised, upper, middle and jointed crucks, classified by where the blades rise and terminate and by whether each blade is a single timber. In England the type is concentrated in the west, the Midlands and the north, and is largely absent from East Anglia and the south-east. Alcock (1981) provides the standard catalogue, since extended by the Vernacular Architecture Group, and dendrochronology has transformed the dating of the type. Blade feet are vulnerable to decay where they sit on or in the ground, and many have been cut off and underbuilt.

C

  • /ˌdendrəʊkrəˈnɒlədʒi/ (dating method) The dating of timber by matching its sequence of annual growth-ring widths against regional master chronologies. In English buildings oak is the principal species dated, sampled by cores taken with a hollow borer from timbers with sufficient rings, usually at least fifty. Precision depends on the survival of the outermost rings. Where the bark edge is present, a felling date can be given to a precise year and often a season. Where only some sapwood survives, a felling date range is estimated using sapwood statistics, such as the 9 to 41 ring estimate for England and Wales given by Miles (1997). Where heartwood alone survives, the result is only a date after which the tree was felled. Because medieval carpenters generally worked unseasoned timber, felling dates usually approximate construction dates within a year or two. The principal interpretive cautions are reused timber, imported Baltic oak, and confirming that sampled timbers belong to the phase in question (English Heritage 2004).

D

  • /ˌefləˈresəns/ (material decay) A deposit of soluble salts on the surface of masonry, brickwork or plaster, formed as salt-bearing moisture evaporates. Crystallisation beneath the surface is termed subflorescence or cryptoflorescence and is the more damaging form, causing powdering, flaking and spalling as crystal growth exerts pressure within the pores. Common salts are sulphates, chlorides and nitrates, derived from groundwater, sea spray, de-icing salts, cementitious materials, gypsum plasters, and former uses such as stabling or storage. Chlorides and nitrates are hygroscopic and absorb moisture from the air. Salt-contaminated plaster may therefore register as damp on an electrical meter without any liquid water source, a frequent cause of misdiagnosed rising damp. Gravimetric testing of drilled samples, measuring both moisture content and hygroscopic moisture content, gives a more reliable diagnosis.

E

  • /ˈfækəlti/ (ecclesiastical regulation) A permission granted by the consistory court of a Church of England diocese, presided over by the diocesan chancellor, for works to a church building, its contents or its churchyard. The faculty jurisdiction operates under the ecclesiastical exemption, by which listed places of worship of denominations with approved internal control systems are exempt from listed building consent. Planning permission is still required where relevant. The Diocesan Advisory Committee advises on applications, and certain works require consultation with Historic England, the local planning authority and the national amenity societies. The Faculty Jurisdiction Rules 2015 introduced List A and List B, covering minor works that may proceed without a faculty or with the archdeacon's consent. For proposals that would harm significance, courts apply the framework of questions set out by the Court of Arches in Re St Alkmund, Duffield (2013), which weighs the seriousness of the harm against the clarity of the justification and the public benefit.

  • /ˈflɔːntʃɪŋ/ (Masonry) Mortar placed to deflect rain water on a chimney or ashlar stone quoins or other masonry protrusion.

  • /ˈflʌʃwɜːk/ (masonry decoration) Decorative facing in which knapped flint is set flush within panels of dressed freestone to form blind tracery, geometric patterns, monograms and inscriptions. It is concentrated in East Anglia, chiefly Suffolk and Norfolk, where it flourished between the fourteenth and early sixteenth centuries and is associated with church building funded by the wool and cloth trades. Holy Trinity, Long Melford, and St Edmund, Southwold, are well-known examples. Flushwork is distinct from chequerwork, in which squares of flint and stone alternate in a simple pattern. The technique depends on the bond between impermeable flint and soft lime mortar. Typical defects include loss of flints, decay of the limestone framing, and damage from hard cement repointing.

F

  • /ˈɡæl.ɪt.ɪŋ/ (Masonry)‍ ‍Also GARRETING or GARNETING, this is the insertion of small stone chips, flint flakes or other fragments into mortar joints while the mortar is still soft. Its function is debated. Suggested purposes include reducing the volume of mortar in wide joints, limiting shrinkage, packing irregular stones, and decoration, and these roles may have coincided. It is characteristic of parts of south-east England and East Anglia, for example ironstone galleting on the greensand buildings of Surrey and the Weald, and carrstone galleting in west Norfolk. The name derives from the French galet, a pebble. Galleting is easily lost during repointing, so it should be recorded before work begins and reinstated to match in size, material and density.

G

  • /ˈhæməbiːm/ (roof construction) A roof type in which short horizontal timbers, the hammer beams, project inwards from the wall head, supported from below by arch braces and carrying hammer posts and further braces above. The arrangement allows a wide span without a tie beam across the full width. Westminster Hall, reroofed in the 1390s by the carpenter Hugh Herland across a span of about 20 metres, is the principal example. Double hammerbeam roofs, with two tiers of hammer beams, occur in East Anglian churches, often with carved angels at the beam ends. The structural behaviour of the type has been debated, and Courtenay and Mark (1987) analysed how loads are resolved in the Westminster Hall roof. Common defects include spreading of the wall heads, joint failure and insect attack. Deathwatch beetle damage at Westminster Hall led to a major repair between 1914 and 1923 that introduced concealed steelwork.

  • /haɪˌdrɒlɪk ˈlaɪm/ (binders)

    A lime that sets partly through chemical reaction with water, in addition to the slower carbonation by which all limes harden. Hydraulicity derives from reactive silicates and aluminates formed when limestone containing clay or silica impurities is burnt, or from the addition of pozzolanic materials. Non-hydraulic or air lime, by contrast, sets by carbonation alone and is supplied as lime putty or dry hydrate. John Smeaton's experiments during the building of the Eddystone Lighthouse (1756 to 1759) identified the role of clay impurities in hydraulic set. Under BS EN 459-1:2015 natural hydraulic limes are designated NHL 2, NHL 3.5 and NHL 5, the figure indicating minimum 28-day compressive strength in megapascals. The permitted strength range within each grade is wide, and conservation practice has moved away from routine use of NHL 5 towards weaker, more permeable mortars. Recent research has also renewed interest in hot-mixed mortars, made by slaking quicklime with aggregate, as a closer match to much historic work.

H

I

  • /ˌɪntəˈstɪʃəl ˌkɒndenˈseɪʃən/ (building physics)

    Condensation that forms within the thickness of a wall, roof or floor where water vapour passing through the construction reaches a layer at or below its dew point. In traditional solid-walled buildings the risk arises chiefly when internal insulation, vapour-resistant membranes or impermeable finishes are added, because these make the outer masonry colder and wetter and reduce its capacity to dry. Timber embedded in the wall, such as joist ends, lintels and wall plates, is especially vulnerable. The Glaser method in BS EN ISO 13788 is a steady-state calculation of vapour diffusion alone. It takes no account of liquid moisture transport, moisture storage, driven rain or solar drying, and is therefore unreliable for traditional construction. BS EN 15026 sets out dynamic hygrothermal simulation, which models these processes over time, and BS 5250:2021 recognises the limitations of the Glaser method and refers to BS EN 15026 where they apply. Retrofit proposals for historic buildings should rest on a moisture risk assessment informed by the building's condition, exposure and significance.

  • /ˈdʒeti/ (timber framing) The projection of an upper storey beyond the face of the storey below in a timber-framed building. The floor joists are cantilevered over the lower wall plate and carried at their outer ends by a bressumer, which also receives the studs of the upper wall. Where a building is jettied on two adjacent sides, a diagonal dragon beam receives joists from both directions. Proposed explanations include gaining floor area on restricted urban plots, reducing mid-span deflection of the joists by counterbalancing, protecting lower walls from rain, and display, and no single cause is accepted. The Wealden house combines jettied end bays with a recessed central open hall under a continuous roof. Jetties were often underbuilt in brick in later centuries, and decay of joist ends and bressumers is a recurrent defect.

J

K

  • /ˈkɪŋ pəʊst/ (roof construction)

    A vertical timber rising from the centre of a tie beam to the apex of a roof truss. Two forms should be distinguished. In many medieval and later roofs of northern England the king post supports a ridge piece and is braced by struts to the principal rafters, working in compression. In the engineered king post truss of the eighteenth and nineteenth centuries the post acts in tension, suspending the centre of the tie beam from the head of the principals, and is secured at its foot by an iron strap or stirrup. Wrought iron king rods later replaced the timber post in many trusses. The king post should not be confused with the crown post of south-eastern medieval roofs, which rises from the tie beam to a collar purlin and stops short of the ridge. In survey, a tension truss should be checked for separation at the post foot, corroded straps and sagging of the tie beam. Misreading a hanging post as a compression member can lead to repairs that fail to restore the connection at its foot.

L

  • /ˌlɪstɪd ˈbɪldɪŋ/ (heritage legislation)

    A building included on the statutory list of buildings of special architectural or historic interest. In England listing is governed by the Planning (Listed Buildings and Conservation Areas) Act 1990 and is carried out by the Secretary of State for Culture, Media and Sport on the advice of Historic England, with entries held on the National Heritage List for England. Buildings are graded I (exceptional interest), II* (particularly important buildings of more than special interest) and II (special interest), in approximate proportions of 2.5, 5.8 and 91.7 per cent. Protection extends to the whole building including its interior, to objects and structures fixed to it, and to structures within its curtilage built before 1 July 1948. Since the Enterprise and Regulatory Reform Act 2013, a list entry may expressly exclude such objects, structures or parts of the building. Listed building consent is required for demolition and for alteration or extension affecting the building's character as one of special interest, and unauthorised works are a criminal offence. List descriptions historically served to identify a building rather than define its interest, so the absence of a feature from the description does not mean it is unprotected. Scotland, Wales and Northern Ireland operate separate systems.

  • /ˌmæθəˌmætɪkəl ˈtaɪlz/ (cladding)

    Clay tiles shaped so that, once fixed, their exposed faces resemble brickwork. They were hung on battens or boarding, or bedded in mortar, over timber-framed or other walls, and the joints were pointed to complete the effect. They are found chiefly in south-east England, particularly Sussex and Kent, from the eighteenth to the mid-nineteenth century, with notable concentrations in Lewes and Brighton, where the Royal Crescent is faced in black glazed tiles. The common claim that they were devised to evade the Brick Tax of 1784 is doubtful, because the Act taxed tiles as well as bricks. Fashion and the economical refronting of timber-framed buildings are the more convincing explanations. Identification relies on close inspection at corners, reveals and junctions, where purpose-made corner tiles or timber details may show. Defects include corroded fixings, slipped or cracked tiles, and decay of the timber substrate.

M

N

  • /ˈnɒɡɪŋ/ (timber framing)

    Brick infill set between the posts, studs and rails of a timber frame, laid in stretcher bond or in decorative patterns such as herringbone and diagonal work. Brick infill was used in some higher-status buildings from the sixteenth century, but in many frames it replaced original wattle and daub during later repair or modernisation. Stave holes and grooves in the framing members indicate the earlier infill. Nogging is considerably heavier and stiffer than daub. It adds load to sole plates and posts, and differential movement between rigid brickwork and a flexible, shrinking frame opens gaps at the interface. Water entering those gaps is held against the timber, and decay of sole plates and the lower ends of studs and posts is a common consequence, aggravated by cement mortars and renders. In modern carpentry the term also denotes short horizontal members fixed between studs or joists, which is a separate meaning.

O

  • /ˈəʊdʒiː/ (architectural form)

    A double curve combining concave and convex sections in an S-shaped profile. As a moulding it appears in classical architecture as the cyma recta and cyma reversa. In Gothic architecture the ogee arch, formed by two reverse curves meeting at a point, appears in England at the end of the thirteenth century, and the Eleanor Crosses of the 1290s are often cited as early examples. It is characteristic of the Decorated style of the first half of the fourteenth century, where it shapes flowing tracery, niche heads and nodding canopies, and it persisted in Perpendicular work before its revival in eighteenth-century Gothick design. The ogee is one of several moulding profiles used to date medieval work, an approach developed for English Gothic by Morris (1978, 1979). The word derives from the French ogive, which now means a diagonal rib or pointed arch, and the shift in meaning is not fully explained.

  • /ˈpælɪmpsest/ (building analysis)

    Originally a manuscript whose text was erased so the writing surface could be reused. In building archaeology the term describes a structure bearing traces of successive phases of construction, alteration and use, each partly overlying or removing evidence of the one before. Reading a building in this way means establishing a relative sequence from the physical relationships between elements, such as straight joints, abutments, blocked openings, roof creases, redundant mortices and peg holes, and changes in material or tooling. Harris (1979) set out principles of archaeological stratigraphy, including the Harris matrix, which have since been adapted to standing structures. The concept supports the position in Article 11 of the Venice Charter that valid contributions of all periods should be respected rather than removed in pursuit of an original form.

  • /ˌfəʊtəʊˈɡræmətri/ (measured survey)

    The derivation of measurements and three-dimensional geometry from overlapping photographs. Albrecht Meydenbauer developed architectural photogrammetry in Germany from the late 1850s, and the technique was long practised through stereo-photography and rectified photography. Current practice relies mainly on structure-from-motion and multi-view stereo processing, which generate point clouds, textured meshes and orthophotographs from large image sets. Accuracy depends on survey control, usually established by total station or GNSS, and on image overlap, resolution and lighting. Photogrammetry complements terrestrial laser scanning and suits stone-by-stone elevations and condition mapping, but performs poorly on uniform, reflective or obstructed surfaces. Historic England's Metric Survey Specifications for Cultural Heritage (2015) sets out standards. Measured outputs still require interpretation by a surveyor familiar with the building before they become an analytical record.

  • /pɪˈsiːnə/ (ecclesiastical fittings)

    A shallow stone basin with a drain, usually set in a niche in the wall south of an altar, used for washing the sacred vessels after Mass. The drain discharged into the wall or ground so that water that had touched the consecrated elements was disposed of reverently. Double piscinae, with two basins, are characteristic of the later thirteenth and early fourteenth centuries, one basin probably serving for the vessels and the other for the priest's hands. A piscina is often grouped with sedilia, the stepped stone seats for clergy on the south side of the chancel. A piscina in an aisle, transept or chapel is reliable evidence of a former altar and is therefore important in reconstructing the arrangement of a church before the Reformation.

P

  • /kwɪŋˌkweniəl ɪnˈspekʃən/ (church building management)

    The inspection of a Church of England church at least once every five years by an architect or surveyor approved by the diocese. The requirement was introduced by the Inspection of Churches Measure 1955 and is now contained in the Care of Churches and Ecclesiastical Jurisdiction Measure 2018. The resulting report, known as the QI, records the condition of the fabric and sets out recommended works in order of urgency. The inspection is visual and non-intrusive, made from ground level, accessible roofs, towers and ladders. The report should state its limitations and recommend specialist investigation where required. The QI informs the parish's maintenance planning and supports applications for faculties and grant funding.

  • /kɔɪn/ (masonry)

    A dressed stone or brick at the external angle of a wall, typically laid with long and short faces alternating on each return to bond the two wall faces together. The word is a variant of coin, in the sense of a corner or wedge, and is sometimes pronounced /kwɔɪn/. Long-and-short work, in which tall upright stones alternate with flat horizontal slabs, is diagnostic of late Anglo-Saxon masonry, as at All Saints, Earls Barton, Northamptonshire. In classical architecture quoins are often rusticated, or contrasted in colour and material, to emphasise the corners of a facade. Quoins often survive where adjacent walling has been altered or extended, and an earlier quoin embedded in later work is a useful indicator of phasing.

Q

R

  • /ˈruːd skriːn/ (ecclesiastical fittings)

    A screen of timber or stone dividing the chancel from the nave of a medieval church. It stood beneath the rood, a carved crucifix flanked by figures of the Virgin Mary and St John, which was usually carried on a beam or on a rood loft reached by a stair built into a wall or pier. Roods were removed under Edward VI in the late 1540s, and a royal order of 1561 required rood lofts to be taken down while the screens were retained. Many screens therefore survive without their lofts, particularly in East Anglia and the south-west, often with painted panels of saints whose faces were defaced by iconoclasts. Where the screen has gone, blocked upper and lower doorways of the rood stair, together with beam sockets and corbels around the chancel arch, record its former position and height. Painted screens require assessment by a conservator before cleaning or repair, since successive paint schemes and later overpainting are themselves evidence.

  • /sɪɡˈnɪfɪkəns/ (conservation principle)

    The National Planning Policy Framework (NPPF) defines significance as the value of a heritage asset to present and future generations arising from its heritage interest, which may be archaeological, architectural, artistic or historic. It is the central concept of values-based conservation. The Burra Charter (Australia ICOMOS, first adopted 1979, last revised 2013) frames cultural significance in terms of aesthetic, historic, scientific, social and spiritual value. English Heritage's Conservation Principles (2008) used evidential, historical, aesthetic and communal values, and Historic England Advice Note 12 (2019) aligned guidance on statements of significance with the NPPF terms. Planning and faculty decisions assess harm against significance, and a proportionate statement of significance is expected with applications affecting heritage assets. For the surveyor, understanding significance precedes specifying repair, because it establishes which fabric and characteristics must be retained.

  • /ˈspɔːlɪŋ/ (material decay)

    The detachment of fragments or flakes from the surface of stone, brick, render or concrete. Principal causes include freeze-thaw action in saturated material, salt crystallisation, expansion of corroding iron cramps, dowels and fixings, and fire. Hard cement mortars are a frequent contributor because they are denser and less permeable than the units they bond. Moisture then evaporates through the faces and arrises of the stone or brick rather than through the joints, concentrating salt and frost damage in the units. This reverses the principle that mortar should be weaker and more permeable than the masonry and act as the sacrificial element. Terminology for stone decay varies between disciplines. The ICOMOS-ISCS Illustrated Glossary on Stone Deterioration Patterns (2008) gives standard definitions separating spalling from scaling, contour scaling, delamination and blistering.

  • /skwɪnt/ (ecclesiastical architecture)

    An oblique opening cut through a wall or pier to give a line of sight to the high altar from a position where the view was otherwise blocked, such as a side chapel, transept or aisle. Its main purpose was to allow a priest at a subsidiary altar, or others in the church, to see the elevation of the Host. It is also termed a hagioscope (/ˈhæɡiəskəʊp/), a nineteenth-century antiquarian coinage from the Greek for holy and to look. Squints are distinct from low side windows, small openings low in the chancel wall once popularly called leper windows. That explanation is now discounted, and the function of low side windows remains uncertain. Squints are often evidence of former altars and of alterations to the internal arrangement of a church.

S

T

  • /ˈtreɪsəri/ (Gothic architecture)

    The ornamental stonework dividing the upper part of a Gothic window, or applied as blind decoration to walls, screens and panelling. Plate tracery, in which openings are cut through a solid slab of masonry, was superseded by bar tracery, in which the pattern is formed from thin moulded mullions continued into the window head. Bar tracery was developed at Reims Cathedral from about 1211 and introduced to England at Westminster Abbey from 1245. English forms are conventionally classed as geometrical, intersecting, curvilinear or flowing, and Perpendicular or panel tracery, in a sequence broadly aligned with the Early English, Decorated and Perpendicular periods proposed by Rickman (1817). Tracery is a principal tool in dating church fabric, though windows were often inserted into earlier walls and many were replaced during nineteenth-century restoration. Common defects include decay of weathered or face-bedded stone, and cracking and spalling caused by corroding iron saddle bars and stanchions set into the stonework.

U

  • /ˌʌndəˈpɪnɪŋ/ (structural repair)

    The deepening or strengthening of a foundation by extending it to a more competent stratum, traditionally with mass concrete placed in short sequenced bays and more recently with mini-piles and needle or ring beams. Historic buildings often have shallow foundations or none, and lime mortars allow them to accommodate slow movement with limited distress. Much cracking in old buildings reflects historic movement that has long since stabilised. The first diagnostic question is therefore whether movement is progressive. This is established by monitoring over at least a full seasonal cycle, using tell-tales, crack-width gauges and level surveys, and by investigating common causes such as leaking drains, trees on shrinkable clay soils and poor surface drainage. BRE Digest 251 provides a widely used classification of crack damage. Partial underpinning creates a stiff zone beside unaltered foundations and can cause new differential movement at the junction, so conservation practice treats it as a last resort once the causes of movement have been addressed.

V

  • /vuːˈswɑː/ (masonry arches)

    A wedge-shaped stone or brick forming one unit of an arch or vault. The central voussoir at the crown is the keystone, and the lowest on each side is the springer. The inner curve of the arch is the intrados and the outer curve the extrados. Masonry arches are generally assessed using the approach developed by Heyman (1966, 1995), which assumes that masonry has no tensile strength, effectively unlimited compressive strength, and does not slide. On those assumptions an arch is safe if a line of thrust in equilibrium with the loads can be found lying wholly within the masonry. Movement of the abutments produces hinges, visible as cracks opening alternately at intrados and extrados, and collapse requires a four-hinge mechanism. Dropped voussoirs, open joints and spreading supports are the principal defects to record in survey.

W

  • /ˌwɒtəl ən ˈdɔːb/ (timber framing)

    The traditional infill of timber-framed panels, formed of a woven lattice coated with an earth plaster. Vertical staves were sprung into auger holes in the underside of the upper rail and a groove in the top of the lower rail, and flexible rods, commonly hazel, were woven between them. The daub, a mix of clay or subsoil with straw or hay, animal hair and dung, was pressed onto both faces and finished with lime plaster or limewash. The panel is light, flexible and vapour-permeable, and accommodates movement in the frame without damaging it. Surviving original panels carry evidence of materials and technique and should be repaired rather than replaced where possible. Common threats include replacement with cement-based or rigid infill, impermeable coatings, and failure of the joint between panel and frame, which admits water to the timber.

X

  • /zesˈtəʊbiəm ˌruːfəʊvɪˈləʊsəm/ (timber decay)

    The deathwatch beetle, a wood-boring insect that attacks hardwoods, principally oak, in which fungal decay is already present. Larvae tunnel through the timber for several years, and in damp, poor conditions for up to a decade, before pupating and emerging in spring through round flight holes about 3 millimetres in diameter. The common name comes from the tapping sound adults make against the timber to attract mates. Because infestation depends on moisture and fungal decay, it concentrates in wall plates, bearings in wet masonry, and timbers below leaking gutters and valleys. The conservation approach set out by Ridout (2000) treats moisture control and removal of the conditions for decay as the primary remedy, and finds routine insecticide treatment of little value in large oak sections. Survey should distinguish active from historic infestation, for example through fresh bore dust and clean flight holes, before any treatment is specified.

Y

  • /jelm/ (thatching)

    A bundle of wetted straw, drawn and straightened by hand, prepared for laying in long-straw thatching. The process, known as yelming, produces layers of straw with the stems roughly aligned, which the thatcher lays on the roof and secures with spars and sways, with liggers (horizontal hazel rods fixed across the surface) at the eaves and gables. Long straw is one of three principal English thatching traditions, alongside combed wheat reed, associated especially with the south-west, and water reed, associated with Norfolk. Thatch is normally renewed by adding a new coat over earlier layers, and base coats in some southern English buildings date from the late medieval period. Letts (1999) showed that smoke-blackened base coats preserve plant remains of archaeobotanical importance, and stripping to the rafters is generally discouraged for this reason. Changes of thatching material or style can affect local character and may require consent where a building is listed.

Z

  • /ˌzəʊəˈmɔːfɪk ˈɔːnəmənt/ (architectural sculpture)

    Decoration based on animal forms, real or imagined. In England it is particularly associated with Romanesque sculpture, including beakhead ornament, a series of bird or beast heads biting over a roll moulding, as on the west doorway of St Mary, Iffley, Oxfordshire. The corbel table and south doorway at Kilpeck, Herefordshire, attributed to the twelfth-century Herefordshire School, include serpents, dragons and other creatures. Zoomorphic forms continue in Gothic work as gargoyles, label stops, bench ends and misericords. Interpretations range from symbolic and moralising readings to protective and purely decorative functions, and intended meanings are rarely documented. Carved detail of this kind is exposed and vulnerable to weathering, and the Corpus of Romanesque Sculpture in Britain and Ireland provides a photographic record against which condition can be compared.